Java Reference
In-Depth Information
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In Figure 1.3, the size (y-axis) refers to the download dimension of the JRE installation
package, and the 1996-figure (JDK 1.0.2) refers to a development kit, which includes
a compiler and other tools. The x axis lists the release year for each version. This data
refers to Win32 versions.
More importantly, the Internet connections are improving relentlessly, so that paradoxically, it
is now quicker to download the 5MB bundle for the J2SE JRE for Windows than it was to
download the smaller JDK 1.0.2 package in 1997. As we will see, this plays an important role
in favoring new software deployment techniques.
If Java wants a bigger role on the desktop scene, it needs to land soundly, that is, to gain the
capability to run full-fledged applications with the latest JREs, on that ground. This can be
compared to the ancient epic story of the Troy siege, where Greeks resort to a gigantic wooden
horse to fool Trojans and penetrate the city. Probably Sun engineers do not need to be as astute
as Ulysses, but they won't progress very far if they don't find the correct solution. We will
address a proposal in Part III, “JNLP.”
Virgin Lands
Apart from the fiercely fought battle for Web-enabled desktops, there is much more promising
and (apparently) easy ground to be won on handheld, wireless devices and other specialized
hardware. These devices are addressed by the J2ME edition, the Java Card, and the Java
Embedded Server technologies. Also, Jini Technology will play an important role in this
market.
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Embedded devices are all devices based on simple microprocessor architectures—sim-
ple because they are designed to run only very specialized programs, unlike PCs,
where hardware is designed to run different kinds of programs. For example, a coffee
machine cannot run a spreadsheet program because its hardware is specialized for
certain operations only. The same is true for a PDA (Personal Digital Assistant) or a
cell phone. Because of their focused nature, embedded devices can vary greatly from
one another. Differences are captured in the APIs that each device supports. Sun has
defined special configurations and profiles to address this problem. When two
devices are said to belong to the same configuration they share a common, minimum
set of APIs. Differences are described using profiles. An example of a profile is the
J2ME Mobile Information Device profile, or MIDP.
